1. Field of the Invention
This invention relates generally to a compact fluorescent lamp provided with a screw base, and more particularly to the structure of a chassis member to which is attached a ballast, a winding envelope and other equipment.
2. Description of the Prior Art
Fluorescent lamps have been used as a general source of illumination for many years. A fluorescent lamp has high lighting efficiency and a low consumption of electric power in comparison with an incandescent lamp and therefore a compact fluorescent lamp provided on an incandescent lamp base, i.e. an E 26-type screw base, has been developed. But in the order to interchange an incandescent lamp with such a compact fluorescent lamp, it is necessary for the fluorescent lamp to have a folded envelope because, in order to obtain about the same brightness as with an incandescent lamp, it is necessary for the fluorescent lamp's envelope to have a certain minimum length. Such a compact fluorescent lamp is known, for example from U.S. Pat. Nos. 3,953,761 and 4,199,708. Such a fluorescent lamp has a lamp base providing a plurality of screw thread portions, a screw base which is secured to the thread portions of the lamp base, a globe, a partition plate dividing the base side and the globe side, a winding envelope and a ballast provided to the partition plate, in which screw threads are formed on both the lamp base and the screw base itself. However, as the screw base is mounted directly to the lamp base in a conventional lamp, it is necessary for the lamp base to be subjected not only to a torsion moment when attaching to a socket but also to the total weight of the lamp including a heavy ballast, a winding envelope and other equipment attached by way of the partition plate. So it is desirable that the connection between the screw base and the lamp base be modified.
Moreover, a lead wire which is connected to the edge of the screw base is wired along the screw thread portions of the lamp base. Therefore when the screw base is fixed by screwing to the screw thread portions of the lamp base, the lead wire moves according to the moving of the screw base. Consequently, the position of the lead wire relative to the screw base can not be determined uniformly, so the efficiency of the next soldering step decreases.
Moreover, it is desirable from the standpoint of safety, that the many lead wires of the winding envelope, the ballast and the glow starter are arranged so that they can not be directly touched by fingers.